The problem with quarantining for me is that I don't have an extra heater or even filter cartridges and my parents won't let me buy that just so I could use it for one week... I have a spare 1.5 gallon, can I just use that without a filter and heater?

Don't they get stressed from all that flaring?

1.5 is fine for a QT for a week or two. You will need to do 100% water changes at least every week.